Salt of a thiuronium base and an acid of phosphorus



lic deposit from this source.

Patented July 29, 1952 SALT OF A THIURONIUM BASE AND AN ACID OF PHOSPHORUS Louis A. Mikeska, Westfield, N. 1., assignor to Standard Oil Development Company, a corporation of Delaware No Drawing. Application December 6, 1949, Serial No. 131,493

5 Claims.

This invention relates to mineral oil compositions and particularly mineral lubricating oils containing a detergent additive.

The art of metallic detergents for lubricating oil compositions adapted for use in internal com bustion engines is well known to those versed in this field and has resulted in substantial improvements in lubricants. These detergents are particularly useful in lubricating oil compositions which are employed in internal combustion engines used in the operation of automobiles, aircraft and similar vehicles, including diesel engines, to improve their operation by preventing or retarding corrosion, piston ring sticking, cylinder wear, and carbon and varnish formation. However, when metallic detergents are used in lubricating compositions where oil consumption is high and engine conditions are severe, such as in aircraft engines or where such concentrations of metallic detergents are used to maintain engine cleanliness under conditions where high depositfuels of cracked or high sulfur nature are used, such as in automobile and diesel operation, the ash content from the metallic detergent accumulates in the combustion chamber and tends to cause pre-ignition, detonation, spark plug fouling, valve burning, and ultimate destruction of the engine.

It has been found, in accordance with the present invention, that if a salt of a thiuronium base (isothiourea) and an acidof phosphorus is employed as an additive for a crankcase mineral lubricating oil orother type of mineral oil, the deposition of carbon deposits and the formation of sludge will be substantially inhibited, and because the additive contains no metal, there will be no accumulation of ash or other metal- These compounds are effective not only when added directly to the crankcase lubricant but also when added to the engine fuel, since in the operation of the engine it will work its way from the combustion chamber into the crankcase and there blend with the lubricant.

The thiuronium base which is reacted with the acid of phosphorus to form a, salt useful in accordance with the present invention may be 1 represented by the formula RSC(NH) NH2, where R is an organic group, more specifically an aliphatic hydrocarbon radical, a cycloaliphatic hydrocarbon radical, or an aralkyl radioaL Thiuronium bases are readily obtained in the form of their inorganic acid salts by condensation of thiourea with an organic ester of an inorganic acid, such as a halide or sulfate. The process is illustrated by the equation:

nourimosum-msomm Nll-lal-ICl 2 v The free base may be formed from the salt by reaction with a caustic alkali, as in the equation:

The acid of phosphorus which is employed in forming the salt of a thiuronium base may be any acid of phosphorus, such as phosphoric acid, phosphorous acid and their organo-substituted derivatives, thiophosphoric and thiophosphorous acids, phosphonic acids and thiophosphonic acids, and the acids obtained by reaction of a sulfide of phosphorus with a hydrocarbon material, which are believed to be thiophosphonic acids.

The salts of thiuronium bases and acids of phosphorus which form the subject matter of the present invention may be obtained either by reacting a metallic salt, preferably an alkali metal salt, of an acid of phosphorus with an inorganic acid salt, preferably a hydrochloride, of the thiuronium base, or by direct neutralization of an acid of phosphorus with a free thiuronium base. Organic radicals'of any length of carbon chain may be present in either the thiuronium base or the acid portion of the molecule, provided only that there is a sufl'icient number of carbon atoms in the total number of organic radicals to provide solubility in mineral oil. In general, there should be a minimum of 12 carbon atoms in the salt. Y Y

The organic group of the thiuronium base may be selected from a wide variety of groups. If the group is aliphatic, it may be saturated or unsaturated, straight chain or branched. Typical thiuronium bases which may be employed are those containing methyl, ethyl, isopropyl, n-butyl, tert.-butyl, n-octyl, tert.-octyl, n-decyl, n-dodecyl, tert.-dodecyl, C7 to ,C20'OXO, oleyl, and paraffin wax chain groups. The 0x0 alkyl groups are residues of OX0. alcoholsobtained by the reaction of carbon monoxide and hydrogen upon the olefins obtainable from petroleum products and the hydrogenation of the resulting aldehyde. The alcohols normally have a branched chain structure. The organic groups may also consist of cycloalkyl group, such as a cyclohexyl group, or they may be of aralkyl type typified by by a, benzyl or a substituted benzyl group.

The acids of phosphorus which may be employed in the formation of thiuronium base salts include all types of such acids, including particularly phosphorous and phosphoric acids and their derivatives obtained by substitution of one or two of their hydrogen atoms by organic groups, whether. aliphatic or aromatic, and organo-substituted thiophosphorous and dithiophosphoric acids, particularly those obtainable by the reaction of sulfides of phosphorus with alcohols and phenols, also phosphonic and thiophosphonic acids. The organic groups in the organo-substituted acids of phosphorus may be, for example, aliphatic groups, such as alkyl groups varying in chain length from C1 to C30, and they may be straight or branched chain in character and saturated or unsaturated, and'may or may not contain substituent groups such as halogen, hydroxyl, amino or nitro groups. Among these groups, also, the branched chain alkyl groups obtained from x0 alcohols are especially useful and are readily available commercially. The organic groups may also be aromatic groups, such as phenyl, phenyl (including wax-alkylated phenyl) benzyl groups, and the like. Included also are residues of alkylated phenol sulfides. Accordingly, typical examples of acids of phosphorus useful in accordance with the present invention are diisopropyl dithiophosphoricacid, di-Z-ethylhexyl dithiop'hosphoric acid, di-n-decyl dithiophosphoric acid, dioleyl dithiophosphoric acid, .di-wax-alkylated dithiophosphoric acid, .di-wax-phenyl di thiophosphoric acid,'diethyl phosphoric (acid, di- '2-ethylhexyl phosphoric acid, di-in-decyl phosphoric .acid, di-wax-p'henyl phosphoric acid, Ca OX0 thiophosphorous acid, and the like. .A group of special interest comprises .the alkylaryl hydroxymethyl p'hosphonic acids, .e. g. '-heptadecyl phenyl 'hydroxymethyl phosphonic acid.

Agroup of acids of special interest "in connection with the present invention include the acidic materials-obtained when a sulfide of phosphorus, especially phosphorus pentasulfide, is reacted with a hydrocarbon, whether paraffinic, .olefinic, or aromatic. The reaction products are believed to-bethiophosphonic acids. In preparing acidic material of this type any sulfide of phosphorus may be employed such as P283, PzSaP-cSB .or P487, 'ora mixture of tWo or more phosphorus sulfides. The hydrocarbon materials which may be reacted with -a phosphorus sulfide may be parafiinic, olefins, or olefin polymers, diolefins, acetylenes, aromatics or alkyl aromatics, cycloaliphatics, petroleum fractions, such as lubricating oil fractions, petrolatums, waxes, cracked cycle stocks, or condensation products of petroleum fractions, solvent extracts of petroleum fractions, etc. Typical materials among these general classes which have been found tobe particularly desirable are bright stock residuu-ms, lubricating oil distillates, octadecene, olefin polymers of molecular weight ranging from 1 00-to 50,000,, copolymers of low molecular weight olefins and diolefins, benzene, 'alkylated and halogenated benzene, and similar derivatives of other aromatic hydrocarbons.

The phosphorus sulfide-hydrocarbon reaction product 'may be readily obtained by reacting the phosphorus sulfide with the hydrocarbon at a temperature of about 200 F. to about 600 F., preferably from 300 to 550 using from about one to about ten'molecular proportions of hydrocarbon to one molecular proportion of sulfide of phosphorus in the reaction. Usually it is desirable tp 'enrploy an amount of phosphorus sulfide that will completely react with the hydrocarbon so that no further purification becomes necessary, and to employ an atmosphere of nitrogen above the reaction mixture. A reaction time of 2-10 hours is frequently necessary to cause the maximum amount of phosphorus sulfide to react.

.alkylated The acid of phosphorus, of whatever type, may be reacted directly with a thiuronium base, or it may be converted into ametalli c salt, such as sodium salt, by reaction lWlth sodium ,rnethylate,

and then reacted With a hydrochloride of the thiuronium base. ,In the latter case, a metallic 'halide will be formed as a by-product and must be separated. It is advantageous to employ a :SO'IVBIIU, such as benzene, which will dissolve the thiuronium salt as formed and not dissolve the by-product metal halide. It is generally necessary to 'h'eat 'themixture for a short period, preferably at refluxing temperature. The metallic halide may .then be filtered off and the filtrate evaporated to obtain the final product. In the I case of .the reaction of a free acid with a free thiuronium base, it is .sufiicient to merely heat the reactants together on a steam bath for a Short time.

'When additives of the present invention are employed in mineral lubricating oils, they are preferably-added in proportions of about 0.001 to -about 10:0% and preferably- 1.0 to about- 6.0%. The proportions giving the best results w-ill vary somewhat according to thena-ture or the additive and 'the specific purpose which the lubricant is to serve in a given case. For commercial purposes, it is convenient to prepareconcentrated oil solutions in which the amount of additive in the composition ranges from 25% to 50% by weight, and to transport and store them in such 'form. Inpreparing a lubricating oil compositionfor use as a crankcase lubricant the additive concentrate is merely blended. with the base -oil in the required amount.

In certain cases it may be 'found that the effect of adding compounds of thetype described above 150 a lubricating oil will be to increase the detergent efiect of the oil without sufficiently providing oxidation resisting characteristics. In 'suchacase it is advantageous to-add to the'lubricant, 'inad'dition to the additives of the present invention, a substance containing sulfur and/or phosphorus. An organic-sulfur compound may be used for this purpose, particularly a compound capable of being decomposed to give freesulfur at a temperature to which the lubricant is subjected during use. Examples of such organic sulfur compounds are sul'furized mineral oils,-su'l- 'furized'terpenes, sulfurized olefins and-diolefins, sulfurized animal and vegeable oils, sulfurized isobutylenepolymers, etc. 7 I I Below are given detailed descriptions of preparations of examples of mineral oil additive of the type described above as well as results of tests applied to determine the detergent properties of the compound. It is to be understood that these examples are given as illustrations of the'present inventionand are not to be-construed as limiting the scope thereof in any way.

Example 1.- DodecyZ thiuronium heptadecyl- 'phenyl-hydrorymethyl phosphonate V (rt) Dodecyl thiuronium hydrochloride was preparedas follows: g. (0.5 mol) of'dodecyl bromide, 38 g. (0.5 mol) of thiourea, and 250 cc. of 95% ethyl alcohol were placed in a reaction. flask equipped with a return condenser and heated to refluxing temperature on the steam bath for three hours. After cooling, the solution was diluted with ml. of water and 200 m1. of concentrated hydrochloric acid and the mixture cooled in ice. The mixture was filtered to remove the precipitate which had formed, and the filtrate was washed with ether-and air dried. The

product consisted of 152 g. of awhite waxy solid.

(1)) Heptadecyl-phenyl-hydroxy methyl phosphonic acid which has the structure R being the C17 alkyl group was prepared as follows: 826.9 g. (2.4 mole) of stearophenone and 495 g. (3.6 mols) of phosphorus trichloride were charged to a 3-liter 3-necked flask equipped with a stirrer, condenser and thermometer. After stirring for 30 minutes at 50 .C. the mixture was allowed to stand overnight (18 hours) at room temperature (about C.) It was then warmed to 35 C. when 864 g. (14.4 mols)v glacial acetic acid was added and maintained at to C. for five hours with stirring, after which it was allowed to stand overnight at room temperature. The mixture was then saturated with dry hydrogen chloride and heated to C. for one hour, then was transferred to an evaporating dish and placed on a steam bath, where it was blown with nitrogen for 3 hours. The resulting product was dissolved in a mixture of benzol and naphtha and washed with dilute hydrochloric acid, after which the solvents were mostly removed by heating on the steam bath and the last traces removed by applying house vacuum in the presence of nitrogen at 150160 C. The resulting product was a light brown solid melting at 152 C. and having a bromine number of 0.8 and a neutralization number of 216.5.

(0) A reaction flask equipped with a stirrer and return condenser was charged with 21.3 g. (0.05 mol) of heptadecyl-phenyl-hydorxymethyl phosphonic acid prepared as in (b) 200 ml. of absolute ethyl alcohol, 5.4 g. (0.1 mol) of sodium methylate, a solution of 28.1 g. (0.1 mol) of dodeoylthiuronium hydrochloride (prepared as in (a)) in ml. absolute ethyl alcohol, and 100 ml. of benzene. The mixture was refluxed with stirring for one-half hour and then cooled and filtered to remove the precipitated sodium chloride. The filtrate was evaporated to dryness on the steam bath, and the residue consisted of 51 g. of a light colored viscous oil.

Example 2.-Dodecyl thiurom'um salt of P280" polyz'sobutylene (a) Dodecyl thiuronium base was prepared as follows: 50 g. dodecyl thiuronium hydrochloride (prepared as in Example 1 (a) was suspended in water and treated with. 8 g. (0.2 mol) sodium hydroxide dissolved in water. The mixture was extracted with. ether and the ether solution washed with water and dried over sodium sulfate. The ether was removed. by evaporation on the steam bath and the residue consisted of 42 g. of oil which solidified on cooling to a white soft solid.

(b) 1200 g. of polyisobutylene of a molecular weight of about 1200 was placed in a reaction flask and heated to 300 F. 125 g. of PzSs was added and the temperature raised to 400 F. over a two-hour period, and heating was continued at this temperature for three more hours without stirring. This reaction, as is well'known, proceeds approximately as follows:

The mixture was blown with nitrogen for another five hours at 400 F. and filtered. (c) The Pass-treated polyisobutylene, prepared as in (b), was titrated in dioxane solution and was found to have a molecular weight of 931 based on acid titration. 23.27 'g. (0.025 mol) of this product was dissolved in 100 ml. of ether and to this was added 6.1 g. (0.025 mol) of dodecylthiuronium base (prepared as in (a)). The mixture was heated on a steam bath until all the ether had been removed. The product was a light brown, soft resin, readily soluble in mineral oil.

Example 3.-Dodecyl thiuromwm salt of waxphenyl phosphate (a) A wax-phenol was prepared as follows: 450 g. (1.77 mols) of chloroparafiin (containing 14% chlorine) and g. (0.96 mol) of phenol were placed in a reaction flask and heated to 150 F. and 22.5 g. of aluminum chloride was added gradually. The temperature was then gradually raised to 121-132 C. and maintained at this point for 2 /2 hours. Finally the temperature was raised to 177 C. and maintained at this level for one-half hour. The mixture was found to contain a trace of chlorine and was again heated at-177 C. for 15 minutes and then cooled. The mixture was poured into dilute hydrochloric acid, extracted with ether, and washed with water and dried. Light products were removed by distilling to 275 C. overhead. The residue consisted of 319.6 g. of viscous red oil.

(b) Wax-phenyl phosphate was prepared as follows: 82.6 g. (0.15 moll of wax-phenol (prepared as in (0a)), 250 cc. of xylene, and 7.5 g. (0.53 mol) of P205 were placed in a reaction flask and heated to refluxing temperature for 4 hours.

The product was filtered by suction and'the solvent removed under reduced pressure (about 2 mm.) at C. The residue consisted of a very viscous oil or soft resin.

(c) 15.02 g. (0.025 mol) of wax-phenyl phosphate (prepared as in (27)), and 350 cc. of other were placed in a reaction flask and stirred until the phosphate had dissolved. To this mixture was added 50 cc. of water, 1.35 g. sodium methylate (0.025 mol), and 7 g. (0.23 mol) of dodecyl thiuronium hydrochloride (prepared as in Example 1 (a) The mixture was stirred for about one-half hour and transferred to a separatory funnel to remove the'water layer. The ether layer was then evaporated to dryness on the steam bath and the residue treated with benzene and re-evaporated to dryness. The residue was a light yellow soft resin weighing 24 g.

' Example 4.Dodecyl thiuro'nium salt of waxphenyl dithz'ophosphate until all of the phosphate had'been dissolved. To this was added 0.68 g. (0.0126 mol) of sodium methylate, 50 cc. of water .and 3.5 g. (0.0116 mol) of dodecyl thiuronium hydrochloride, prepared as in Example 1' (a) and the'mixture stirred for about /2 hour. The ether layer was separated by filtration and to this was added 100 ml. of benzene and the mixture evaporated to dryness on the" steam bath. Benzene was again added and the mixture re-evaporated to dryness. The product consisted of a light brown, soft resin, readily soluble in mineral oils.

It will be evident that the phosphorus acid compounds, reacted with the thiuronium salts in the above examples, have the general structure where Y is selected from the group comprising aliphaticand aliphatic-phenyl hydrocarbons and their hydroxy derivatives, with or without a linking oxygen atom, X is either sulfur or oxygen, and m and n are each integers of value 1 to- 2, totaling 4.

Example 5.C'drbon black: dispersion test A ca'rbon'black dispersion test was carried out, as described in U. S. Patent 2,390,342, to measure the comparable effectiveness of the additives of the present invention as agents for dispersing sludge in lubricating oils. In this test 6% by weight of activated carbon was added to the oil blend containing the additive and thoroughly dispersed in the oil by stirring with an egg beater type mixer for '15 minutes while the temperature of the oil was maintained at 250 F. If an additive is not a dispersing agent, the carbon black settles rapidly at this point leaving clear oil at the top in an hour or two. A very effective dispersion will maintain the carbon black in suspension so that no change in the opaque slurry is apparent even after a 24-hour period. With all but the most potent dispersing agents stratification occurs with the black layer at the bottom (high concentration of carbon black) and a blue opaque layer at the top (reduced carbon black concentration). Cases of this type, known as blue line separations, are only detectable in reflected light. In the absence of a disperser, or in the presence of a poor disperser, Stratification occurs with the black layer at the bottom and a clear oil layer on top. The base oil used for this test was a parafiinic oil of SAE 30 grade. The results of the test when applied to blends containing the products of Examples 1 to 4 are shown in the following table, in which the results are shown as the volume of the dispersed carbon black remaining after the settling period.

Additive Concentration Carbon Black The above results show that in the case of the blends employed a good dispersion of the carbon black was maintained throughout the period of the .test.

. The products of the present invention may be employed not only in ordinary hydrocarbon lubricating oils but also in the heavy duty type of lubricating oils which have been compounded with such detergent type additives as metal soaps, metal petroleum sulfonates, metal phenates, metal alcoholates, metal al-kyl phenol sulfides, metal organo phosphates, thiophosphates, phosphites and thiophosphites, metal salicylates, metal xanthates and thioxanthates, metal thiocarbamates, amines and amine derivatives, reaction products of metal phenates and sulfur, reaction products of metal'phenates and phosphorus sulfides, metal phenolsulfonates and the like. Thus the additives of the present invention may be used in lubricating oils containing such other addition agents as barium tert.-octylphenol sulfide, calcium tert.-amylphenol sulfide, nickel oleate, barium octadecylate, calcium phenyl stearate, zinc diisopropyl salicylate, aluminum naphthenate, calcium cetyl phosphate, barium di-tert.- amylphenol sulfide, calcium petroleum sulfonate, zinc methyl cyclohexyl thiophosphate, calcium dichlorostearate, etc. Other types of additives such as phenols and phenol sulfides may be employed. They may also be used in the absence of other dispersing agents, but in the presence of various types of antioxidants.

The lubricating oil base stock's used in the compositions of this invention may be straight mineral lubricating oils or distillates derived from paraflinic, naphthenic, asphaltic, or mixed base crudes, or, if desired, various blended oils may be employed as well as residuals, particularly those from which asphaltic constituents have been carefully removed. The oils may be refined by conventional methods using acid, alkali and/or clay or other agents such as aluminum chloride, or they may be extracted oils produced, for example, by solvent extraction with solvents of the type of phenol, sulfur dioxide, furfural, dichlorodiethyl ether, nitrobenzene, crotonaldehyde, etc. Hydrogenated oils, white oils, or shale oil may be employed as well as synthetic oils, such as esters and .polyethers as well as those prepared, for example, by the polymerization of olefins or by the reaction of oxides of carbon with hydrogen or by the hydrogenation of coal or its products. Also, for special applications, animal, vegetable or fish oils or their hydrogenated or voltolized products may be employed in admixture with mineral oils.

For the best results the base stock chosen should normally be that oil whichwithout the new additive present gives the optimum performance in the service contemplated. However, since one advantage of the additives is that their use also makes feasible the employment of less satisfactory mineral oils or other oils, no strict rule can belaid down for the choice-of the base stock. Certain essentials must of course be observed.

'The oil must possess the viscosity and volatility characteristics known to be required for the service contemplated. The oil must be a satisfactory solvent for the additive, although in some cases auxiliary solvent agents may be used. The lubricating oils, however they may have been produced, may vary considerably in viscosity and other properties depending upon the particular use for which they are desired, but they usually range from about 40 to seconds (Saybolt) viscosity at 210 F. For the lubrication of certain low and medium speed diesel engines the general practice has often been to use a lubricating oil base stock prepared from naphthenic or aromatic crudes and having a Saybolt viscosity at 210 F. of 45 to 90 seconds and a viscosity index of to 50. However, in certain types of diesel thickened fatty oils, sulfurized fatty oils, organometallic compounds, metallic or other soaps, sludge dispersers, antioxidants, thickeners, viscosity index improvers, oiliness agents, resins, rubber, olefin polymers, voltolized fats, voltolized mineral oils, and/ or voltolized waxes and colloidal solids such as graphite or zinc oxide, etc. Solvents and assisting agents, such as esters, ketones, alcohols, aldehydes, halogenated or nitrated compounds, and the like may also be employed.

Assisting agents which are particularly desirable as plasticizers and defoamers are the higher alcohols having 8 or more carbon atoms and preferably 8 to 20 carbon atoms, e. g., lauryl alcohol, stearyl alcohol, wax oxidation alcohols, and the like.

In addition to being employed in lubricants the additives of the present invention may also be used in motor fuels, hydraulic fluids, torque converter fluids, cutting oils, flushing oils, turbine oils or transformer oils, industrial oils, process coils and generally as antioxidants or detergents in mineral oil products. They may also be used in gear lubricants and greases. Since they are powerful surface active agents, they have practical use in dry cleaning fluids, mineral, spirit and aqueous paints, in flotation agents, and as dispersants for insecticides in aqueous and nonaqueous solutions and for carbon black in rubber mixes.

What is claimed is:

1. As a new composition of matter a salt 01. an

10 organic acid of phosphorus and an organic base of the type RSC(NH)NH2, where R is selected from the group consisting of aliphatic hydrocarbon radicals, cycloaliphatic hydrocarbon radicals, and aralkyl radicals. I i 2. As a new composition of matter a salt of an organic acid of phosphorus formula writ-( where Y is a hydrocarbon radical selected from the group which consists of aliphatic and aliphatic-phenyl hydrocarbon radicals and their hydroxy derivatives, X is selected from the group consisting of phosphorus and sulfur, and m and 11. are integers each of value 1 to- 2, totaling 4, and dodecyl thiuronium base.

3. A composition according to claim 2 in which to acid of phosphorus is heptadecyl-phenyl-hydroxymethyl phosphonic acid.

4. A composition according to claim 2 in which the acid of phosphorus is a reaction product of a polyisobutylen of about 1200 molecular weight and P285.

5. A composition according to claim 2 in which the acid of phosphorus is di(waxphenyl) phosphoric acid.

LOUIS A. MIKESKA.

REFERENCES CITED The following references are of record in the flle of this patent:

UNITED STATES PATENTS 

1. AS A NEW COMPOSITION OF MATTER A SALT OF AN ORGANIC ACID OF PHOSPHORUS AND AN ORGANIC BASE OF THE TWO TYPE RSC(NH)NH2, WHERE R IS SELECTED FROM THE GROUP CONSISTING OF ALIPHATIC HYDROCARBON RADICALS, CYCLOALIPHATIC HYDROCARBON RADICALS, AND ARALKYL RADICALS. 